Typical commercial hand dishwashing compositions incorporate divalent ions (Mg, Ca) to ensure adequate grease performance in soft water. However, the presence of divalent ions in formulas containing anionic, nonionic, or additional surfactants (e.g., alkyl dimethyl amine oxide, alkyl ethoxylate, alkanoyl glucose amide, alkyl betaines) leads to slower rates of product mixing with water (and hence poor flash foam), poor rinsing, and poor low temperature stability properties. Moreover, preparation of stable dishwashing detergents containing Ca/Mg is very difficult due to the precipitation issues associated with Ca and Mg as pH increases.
U.S. Pat. No. 4,556,509 teaches diacid salts of diamines. Under these conditions, we have found that these materials have limitations. Moreover, the benefits are confined to hardness &lt;70 ppm. U.S. Pat. No. 4,556,509 also teaches the use of C2 spacer, e.g., ethylene diamine diacid salt and ethoxylated diamines, both of which severely limit performance in the current development.
It has now been determined that the use of certain organic diamines, as outlined in detail below, with surfactants in dishcare compositions with pH's .about.8.0-12 (measured at 10% solution) leads to improved cleaning of tough food stains and removal of grease/oil when compared to the use of Mg or Ca ions in conventional detergent compositions. Unexpectedly, these organic diamines also improve suds stability in the presence of soils, esp. soils containing fatty acids and proteins.
Further, the strong grease removal performance of the diamines discussed herein allows reduction/elimination of Mg/Ca ions from the formulation while maintaining benefits in grease performance. The removal of Mg/Ca additionally leads to improved benefits in dissolution, rinsing and low temperature product stability.
The diamines of this invention in combination with surfactants also provides sensory benefits. It has been found that the presence of this composition produces a "silky" feel to wash liquor and a feeling of "mildness" to the skin. The diamines are also found to produce antibacterial benefits to the wash liquor. However, the specific compositions presented herein are especially designed for dishwashing having relatively high pH's, detersive surfactants, and optional enzymes, all of which would be undesirable in contact lens cleaners.
It has now been found thse benefits are achieved through the use of low molecular weight organic diamines in higher pH formulations (.about.8.0-12) across a broad range of hardness (8 to &gt;1,000 ppm).